1. Field of the Invention
The present invention relates, in general, to electro-magnetic acoustic transducers, and in particular, to a new and useful circuit for providing remote tone bursts to an electro-magnetic acoustic transducer.
2. Description of the Related Art
Electromagnetic acoustic transducers (EMATs) are relatively new devices which are used to nondestructively test metal components and structures. EMAT systems have been developed and have been used in an increasing number of applications throughout many types of industry. EMATs can perform ultrasonic inspections without the use of a fluid couplant which is required with conventional piezoelectric ultrasonic transducers. Inspection with EMATs is fast, easy to automate and does not contaminate the component being inspected.
A majority of EMAT applications use meanderline coils to generate acoustic waves directly in the metal components being inspected. This requires the transmission of a few cycles (typically 1 to 16) of radio frequency (RF) alternating current to excite the coil and induce the ultrasonic wave. This high-frequency tone burst is presently provided by a commercially available RF amplifier. Peak tone burst currents required for good EMAT performance are on the order of 100 to 200 amperes. Remote operation of EMATs with currently available electronic instrumentation requires the transmission of these RF currents through cables as long as 200 feet. This results in loss of power, decreased sensitivity and radiation of RF electromagnetic interference signals which can affect instruments and controls in nearby systems.